Airplane engine controller



Aug- 7, 1951 P. SCHNEIDER AIRPLIANE ENGINE CONTROLLER Aug. 7, 1951Original Filed April 24, 1943 2 Sheets-Sheet 2 SPEED caNrRoL BMEZRETHROTTLE RELAY l coNrRoz. GaNTRoL co/Ls ro/vmcrs con/mers co/vrAcrsco/vmcrs co/vrAcrs caNAcrs CONTACTS Co/vmcrs /I/,f/s 2,1/4 `121, Iza12a/4 lag/31 /62/70 lag/a6 /fq/f/ 67C 86C narmally normally normallnormally normally normally normally nor/nulli closed open apen clasedclosed a en closed open Jerrc'nsemcrmse apen at clasez ai rlaseza openaz offen afi closed a? a en ai closeaa speed speed /qaoazpmmoon z/,oooz/,aao 4o" 40" 9a7g1mlle gratl] A-coNTRol. oF MmlMuM SPEED arc //3 j imnl In 96C //2 //4 /22 /z /ia /3/ /35 /J JMW B-,czoNTRol BY THE THTJOTTLEcoNTRoLLER 0F SPEED BETWEEN |0000 MIN` ANID 21000 MAX. 87C Em/H @2m/24Tom/5l 05m/56 8 6C C-c mmol. oF MAmMuM SPEED THR TTLE OPEN AT LEAST 95%87C I /21/ V23l E m T11 ML /fz //4 /22 /24 /30 /3/ m: vf/y D-coNTRoLFoR-AccELERATmN 87C I m f/z )k/f4 /zz /24/30 /31\ E'coNT-RoL. BY EXHAUSTBACK PREs'uRE [LV 87C om I lg; V70 66C* /ZZ )lil/24 cnRclulTs @BEBcob/VEINTE@ HN ENTQR u j ATTORNEY Patented Aug. 7, 1951 AraPLANE ENGINECONTROLLER Paul L. Schneider, Anderson, Ind., assignor to General MotorsCorporation, Detroit, Mich., a

corporation of Delaware Continuation of application Serial No. 484,419,April 24, 1943. rlhis application March 13, 1944,

Serial No. 526,251

14 Claims.

This invention relates to the control of an airplane power plantcomprising an internal combustion engine, a supercharger and an engineexhaust driven turbine which drives the supercharger. rIhe controlsystem of the present invention operates in conjunction with a throttlevalve'regulator responsive to a selected fuel intake pressure whicheffects opening movements of the valve in order that a selected pressurewill be maintained in the fuel intake as altitude increases.

This application is a continuation of application Serial No. 484,419,filed April 24, 1943, now abandoned.

It is an object of the present invention to provide a system of controlhaving speed responsive means for determining the low economical limitand the high safe limit of turb-ine speed, the low speed operation ofthe turbine being such as to maintain a supercharger pressure suicientfor engine requirements during flight in a lower altitude range, andhaving means responsive to movement of the throttle valve by theregulator to substantially wide open position for causing the speed ofthe turbine to increase above the minimum speed to whatever Value isrequired to maintain the selected pressure in a range of altitudes abovethat which was critical for operation of the turbine at minimum speed,the speed increase of the turbine ceasing when maximum speed is reached.The means above referred to is the electrical mechanism which iscontrolled by movement of the throttle, an arm being moved as thethrottle is moved to effect actuation of certain switches to control theoperation of such electrical mechanism in the manner set forthhereinafter. When the pressure selection is abruptly increased and thethrottle valve moves suddenly to wide open position, the system ofcontrol provides for a momentary rapid acceleration of the turbinepreliminary to setting back to the speed required to maintain theselected intake pressure. The object is to provide for rapidlyaccelerating the air during its course through an air cooler and otherair ducts connected with the exhaust turbine at the rear of the airplaneand with the engine carburetor at the front.

While the fuel intake pressure is being maintained it is to be notedthat engine exhaust back pressure is increasing as the waste gate isbeing closed to cause the turbine speed to increase. This system also'provides for limiting the extent to which the waste gate is closed sothat exhaust back pressure will not exceed an amount which is allowedfor turbine operation without seriously i,

reducing engine power output to the propeller.

-Therefore the ultimate critical altitude for a given selected pressureis that which obtains when the throttle has been opened as wide aspossible by the regulator and the position of the waste gate (CL (iO-13)is either such that the speed of the turbine is at the maximum or issuch that the exhaust back pressure does not exceed a certain amount.

ln the disclosed embodiment of the present invention the functions ofthe system are directed to the control of an electric servo-motor whichcontrols the position of the exhaust waste gate.

Further objects and advantages of the present invention will be apparentfrom the following description, reference'being had to the accompanyingdrawings wherein a preferred embodiment of the present invention isclearly shown.

In the drawings:

Fig. l is a diagram of a system of control embodying the presentinvention.

Fig. 2 is a chart of operations of the control system.

Referring to Fig. 1, engine lo drives, through gears 16a and lb, asupercharger Il connected by duct I3 with a carburetor l2 and with anintake manifold i5. The flow of charging air or fuel mixture iscontrolled by a throttle valve I4. Carburetor l2 is connected by a duct|613 with an auxiliary supercharger i6 which receives air entering anair scoop Nia.

The exhaust pipe il, having an outlet branch i3 controlled by waste-gatevalve I9, leads to an exhaust gas turbine 20 which drives thesupercharger iii having a shaft 2 la connected by gears Zio and Zic witha shaft 2id which operates a switch controlling governor 22 comprising amember 23 carrying pivots 23a supporting levers 23h carryingfly balls23o, outward movement of which is restrained by spring 23d. Levers 23oare connected by links 2li with a collar 25 received by a groove in anon-rotatable sleeve supported by the shaft 2id. Sleeve 25 carries pins2l and 28 engageable respectively with levers 27a and 28a pivotedrespectively at 2lb and 23h. These levers have forked end portions whichadapt them for operation upon resilient metal switch blades to bedescribed.

Throttle Valve I4 is under the control of a throttle valve regulatingdevice which determines theextent of opening of the valve I4 in orderyto maintain a selected pressure.

The regulating device has a main control lever 3l which is manuallyoperated from the pilots throttle lever. Lever 3| is secured to a rod orshaft 32 which is supported for rotation in any suitable supportingbracket and movement ofthe lever 3l' operates arms 33 and 3d which arealso secured to the rod or shaft 32. Arm 36 is connected by link 38 witharm 39 attached to shaft i@ attached to throttle valve I4. Arm 31 has acam slot 31a which receives a cam follower roller 3io carried by a link4i `connected by a pin fila with the piston rod i2 of an hydraulicservomotor having a piston 43 slidable in a cylinder 4t and urged towardthe right by a spring t5. Roller 31h is connected also with an arm 31eloosely journalled on shaft 32. Cylinder 44 has ports 46 and 41controlled by a valve 48 having lands 49 and capable of covering bothports 46 and 41 simultaneously, or of placing pressure fluid inlet 5| incommunication with either of these ports.

Arm 33 is connected by link 52 with an arm 53 connected with shaft 53afor rotating a pressure selecting cam 54 against which a lever 55 isurged by a compression spring 56. Lever 55 is fulcrumed at 51 and isconnected by rod 58 with valve 48. Fulcrum 51 is supported by bridge 59connecting the free ends of metal bellows 60 and 6| having their ends 62and 63 respectively, fixed. Bellows 60 is sealed and evacuated. Bellows6I is connected by pipe 64 with the intake manifold I5. The bellows 60contains springs 60a and 80h and bellows 6| contains a spring Gla, saidsprings being so calibrated that fulcrum 51 moves in a predeterminedrelation to changes in engine intake manifold pressure.

The normal or inoperative position of the piston rod 42 is shown.Movement of lever 3| counterclockwise from the normal position showncauses fulcrum 35 to move counterclockwise and the bell crank lever 36,31 to move clockwise since its arm 31 is caused to pivot on roller 31Dwithin the cam slot 31a of arm 31. Link 38 moves right and lever 39 andshaft 40 turn clockwise to open the throttle I4. At the same time lever33 turns counterclockwise, link 52 moves left and levei` 53, shaft 53aand cam 54 turn counterclockwise, thereby causing lever 55 to locatevalve 48 so that pressure fluid inlet 5| communicates with cylinder port41. Then rod 42 moves left to effect Whatever further opening movementof throttle 'valve 4 is required to maintain in the intake passage I5the pressure selected by cam 54 when moved from its normal position bymovement of lever 3| counterclockwise. When the selected pressure isattained, bellows 6| will have expandedto an extent such that fulcrum 51moves to cause valve 48 to be placed in position for closing both ports46 and 41 of cylinder 44. As the altitude increases, rod 42 will movefurther and further toward the left to cause the selected pressure to bemaintained.

The lengths and locations of the levers and the shape of the cam slot31a of the regulator are such that the throttle valve I4 can be moved bythe piston 43 to wide open position for pressure selections over arelatively wide range, as from below normal cruise to emergency. Thisfeature is disclosed more in detail in the copending application ofJorgensen and Taylor, Serial No. 612,392, flled August 24, 1945.

When the throttle I4 has been fully opened to maintain a selectedpressure at a certain altitude, that altitude is critical for thatpressure selection with low speed turbine and supercharger operation.The only way by which a higher altitude can be attained withoutsubstantial loss of power is to increase the pressure in the fuel intakepassage I 5 by increasing the governed speed of the auxiliarysupercharger. That increase is obtained by closing the exhaust turbinewaste gate I9 by means responsive to movement of the valve I4 by thepressure regulating device to substantially wide open position.

The waste gate I9 is controlled by a reversible electric motor whichdrives a shaft 10 connected by a speed reducer 1| and a shaft 1|a with alever 12 connected with a link 13 having a slot 14 receiving a stud 15carried by a lever 16 connected with the waste gate I9. A springenergized and opening of gate I9 stops.

4 11 connects the lever'lB with the link 13 and urges the lever 16upwardly, the stud 15 engaging the link 13 at the upper end of the slot14. This mechanism provides for actuation of the waste gate I9 by anaccelerating device, to be described, independently of the motor 80.

Motor 80 has an armature connected through a commutator 8| with brushes84 and 85. Brush 84 is connected with oppositely wound fields 82 and 83which are separately energized to produce rotation of the armature inopposite directions. Field 82 is connected by relay contacts 88, whenclosed. with relay armature 86a, terminal 88 and wire 89 with a battery90, connected by a switch 9| and a Wire 92 with brush 85. Field 83 isconnected with battery 90 by contacts 81, when closed, and by armature81a, terminal 88 and wire 89. The closing of contacts 88 is effected bythe attraction of armature 86a toward a core 86h when a coil 88e isenergized; and the closing of contacts 81 is effected by the attractionof armature 81a toward a core 81h when a coil 81o is energized.

The control for minimum speed will now be explained. A minimum governedturbine speed of 10,000 R. P. M., for example, is selected as aneconomical speed for turbine operation when the plane is in a loweraltitude range. At that speed the auxiliary supercharger I6 will operatefast enough to overcome friction of the air moving through pipe Ib,carburetor I2, and pipe I3, so that there is no drag on the superchargerSupercharger II will provide the intake pressure required by the engineas the altitude increases from ground level to a medium criticalaltitude which might range from 6000 ft. for a high pressure selectionto 12,000 ft. for a low pressure selection. Until the critical altitudefor low speed operation of the turbine has been reached, the throttle I4is not fully opened and switch contacts |35, |36 adjacent the regulator30 are closed. When the speed attains 10,000 R. P. M., sleeve 26 hasmoved sufficiently to the left to cause pin 21 to release the lever 21ato allow a blade ||0 (which has been confined by prong 21-c) to returnresiliently to normal position as shown, thereby causing its contact |I2to engage a contact II4 in a blade ||6. When contacts |35, |38 and |I2,II4 are closed, relay coil 81o is connected with battery through thefollowing circuit: battery 90, switch 9|, wire 95, wire |26, blade |I0,contacts IIZ, II4, blade IIB, wire |21, blade |20, contacts |22, |24,blade |26, Wire |28, blade |29, contacts |30, I3|, blade |32, wire |33,blade |34, contacts |35, |36, blade |31, wire |38, limit-switch blade|39, contacts |40, limitswitch blade I4I, coil 81e, terminal 88 and Wire89. Contacts 81 close and field 83 is energized to cause armature 8| torotate and to turn lever 12 clockwise and lever 18 counterclockwise toopen the gate I9 and to reduce the turbine speed. When the speed fallsslightly below 10,000 R. P. M. contacts ||2, II4 open. Coil 81C is de-Contacts ||3 close at about 9900 R. P. M., and coil 88e is energizedthrough the following circuit: battery 90, switch 9|, wire 95, wire |28,blade |09, contacts III, ||3, blade II5, wire |42, limitswitch blade|45, contacts |48, limit-switch blade |41, wire |48, coil 86e, terminal88 and Wire 89. Field 82 is energized and the motor 80 turns the levercounterclockwise and the gate I9 moves clockwise toward closed position,and the speed starts to increase. Thus the minimum governed speed ismaintained at slightly below 10,000

5. R; P. ML', byan .alternatev closing ofi contacts: |1I 2, |14, andcontactsV II I1, |I3. These.' control cir.- cuitsl are shownzinsimpliedjform irrFig: 2under A Control ofk Minimumpeed.

As f the altitude increases, the; pressure: regulating device increasesthe opening of throttle I4' in order to maintain. a selected pressuredetermined by the position of cam 59. At about 90% of `full throttlemovement; a lever |09: attached. to throttle operating shaft 402 engagesblade- I 3'4? and separates contacts |35, |36; This removes-.speedreducing control by relay coil B'I'c. At=about195% of'iull throttleopening, lever IJlISJ'Willmove blade |30 further downwardly.: to. causeContactV |50 of blade |30 to engage a contact |'5| of'blade' |522 Thiscauses energization ofrelay. coil dthrough the following circuit:battery 90; switch 9|, wire 95; wire |20', contacts I I2', I4, wire|1211?, contacts |22, |24, wire |28-, contacts |30', |31, wire- |33,contacts |50, I'5|, wire |53, wire |42, limiteswitch contacts |156, wire|081 coil' 86o, terminal 08 and wire 89, Turbine speed increasestocausethe supercharger l5. to increase the available pres:- sure2 Asthe pressure rises, the pressure regulating device: moves thevalve I4`toward closedposition to reduce theA pressureat the engine intakevalves. Contacts |50, |50` open as lever |49 rotatescounterclockwisewith a closing-movement ofy valve Ie to 95% openposition; and'Y contacts |35, |30 close when the valve -I4 is 90%A open,thus placing coil 01e in4 circuit with the battery 90fto cause themotor-80 to open waste-gate I9 and reduce the turbospeed. Then, asaltitude increases, the pressure regulating device opens the valveU-andvcontacts |135, I30'open, and contactsk |50, I5! close, andturbinespeed star-ts increasing. A simplified' showing ofithe control'circuits-described in this paragraph ismade in-Fig. 2-under B. Controlby the ThrottleControllerz Thus the pressure regulating device takes`over control ofj turbine speedA when that altitude is reachedv whichV iscritical for-the'selected intake pressure with low speed operation ofthe auxiliary supercharger I0; As altitude increases,thepressure-regulating device causes thegover-ned speed of the tur-bineto be increased so that when the throttle Iii-is 95% open,theselected-pressurewill be maintained. Therefore the ultimate criticalaltitude for a selected.' pressure is that which exists when thevthrottle is 100% wide open and the pressure regulating devicehas raised'thegoverned turbineA speed tothe maximum.

At maximum-speed, the governingis taken over by the speed responsivedeviceA 212. At about 20,950'R. P, M; for example, pin 28- moves lever28o/left andx its prong- 28o' engages blade |20 to separate contacts|22, |24; At 21,050R. P. M. prong 28d engages blade I|9-to bringAcontacts |21, |23J into engagement. Relay coil 81o is connected with thebattery through the following circuit: battery 90, switch 9|, wire-95;wire |216, contacts II-Zfy I-Iii, wire |27, wire |55; cont'actsfIZlI,|23; wire |56-, wire |38, contacts- |40y coilv 8'|c, terminal 8-8,wire-89: Then the motor 'startsopening gate I9, thespeed drop-s, sleeve26 moves-right, and contacts I 2|, |23' open, at slightly under 21,050R.P'. M. Contacts |22-, I'24closeat'203950 R. P; M., coil 86e isenergized, motor-closes gate I9v and the speed increases. Thereforeaslong as the throttle valvey I0 is 95% open, the maximum governed speedof the turbine is maintained at about 21,000 R. P. M; When theplanedescends from the altitude which is critical for a selectedpressure with maximum turbine speed, the-speed off the turbine is causedto decrease to whatever speed is; necessary to maintain; a selectedpres:- sure with195,%; throttle-opening; The controlcir.- cuitsdescribed in this paragraph are. Shown. in simplified form in Fig. 2under C,. Control. of Maximum Speed.

The systern provided for a momentary rapid acceleration ofV the turbinewhen the pressure selectionis abruptly and considerablyV increased.andtherpressureregulating device quick-ly moves the throttle to fullywide-open position. Byfmalfn-` ing95% throttle opening sufficient tofcause closing'ofcontacts |50, |5.-I, an. additional 5% movement of thethrottle to wide open positionA and correspond-ing movementt ofleverV|49 is.` provided to eiect also the closing: of* contacts |00,v I8Iwhich results in connecting relay coil 91cwith the battery through thefollowing circuit-1; bat',v tery 90', switch 9|, wire 95, wire |26,contacts H2; H4; wire |21-, contacts |22, |20 (closedslightly belowmaximum speed), wire |28, contacts; |30;r |31, wire |133; contacts |50;I5I', contacts |80; I,8-|f, wire |83, coil 91o. A simplifiedv showing. othis circuit is made in Fig; 2 under D. Control:- for Acceleration.Relaycontacts 9"| close to-.conr nect solenoid coil'f 99 with thebattery. Arma.- ture H0 moves up, link |05 moves down", pin |01 isengaged by link |05 at theuppercend of slot I, lever-IS-mcves down andgate |91closes. Immediately there isA rapid acceleration of the turbineto maximum tov increase the speed ofz air movement from the'supercharger I5 to the` car.- buretorv which may be a considerabledistance apart. The attained turbine speed' may exceed the speedrequired 15o-maintain the pressure selected with 95% throttle opening,hencethe pres sureV regulating device will start closing.' the throttleand contacts I-80|8I will open; but', meanwhile, the motorY 30 will beoperating to place the link- 13 in a position such that, when solenoid13 is deenergized byopening thecontacts |80, IBI, the gate I9 willl belocated at least approximately the correct position for effecting aturbine speed'rthat will give the selected pressure when theY throttleis 95% open. If the new Waste gatepositionV is correct toy maintain theproper turbine speed for the pressure selected, the throttle willclose-a little more, andv contacts |50, |51 will open, thus stoppingoperation of'A the motor 80 to close the waste gate; If the new wastegate; position is such that turbine speed is too high, the throttle ILAwill continue to close and' contacts- |35, |35 will'close to causereversal ormotor 80 andl opening of gate I9, thus reducing turbinespeed; If the new waste gate position does not produce a. turbine speedhigh enough to maintain the selected intakepressure after theacceleration period, the throttle again begins to open further. Thiscauses contacts |51' to close or both contacts |50, I 5| and contacts|80, |8| to close, depending on how much below the required spe.ed, theturbine speed was atthe end of the acceleration period. If only contacts|50, I 5|- close, the gate I9 is closed relatively slowly and theturbine speed is raised relatively slowly;

and if contacts |50, |5I- and contacts |80-, |8|

close the gate I9 is quickly,l fully closed and the turbine has a.short, acceleration period. during which the motor operates to fix. a.new,v final position of' greater closing or the gate: I9.

The operation off shaft 'II a isconned toi a travel sufficientonlyto-fully close or fully open the gate I9). For this.l purpose there is alever |58 connected with shaft "Ha which engages limit-switch blades|4|- and I4'5'tooperrthe1limit creases.

switches at times' when rotation of shaft in either direction shouldcease in all events.

The raising of turbine speed by means controlled by the regulator in therange between minimum and maximum will take place provided a.predetermined exhaust back pressure is not exceeded. Below exhaustpressure of 40 Hg. absolute, for example, contacts 30, 3| remain closed,when that pressure is reached contacts |30, |3| open and closing of theWaste gate ceases; and if exceeded, contacts |69 and |'|0 of blades |68and respectively are closed and relay coil 81o is connected with thebattery through the following circuit: battery 90, switch 9|, wire 95,wire |26, contacts ||2, ||4, wire |27, contacts |22, |24,wires |28 and|59, contacts |69, |10, Wire |12, wire |38, contacts |40, coil 8|c,terminal 88, wire 89. Motor 80 opens gate |9, and the turbine speed andexhaust back pressure are reduced. Contacts |30, |3| and contacts |69,are controlled by a bellows IGI connected by pipe |6|a with engineexhaust pipe and tied by a bar |62 to an altitude compensating aneroid|63. When the exhaust back pressure is below 40 Hg., contacts 30, I3|are closed and the maximum governed speed may be maintained in themanner described. When the pressure reaches 40" Hg., pin |66 on bar |62engages lever |64, pivoted at |65, and its tine |65a engages blade |29and contacts |30, |3| are opened. Slightly above 40" Hg., tine |651)engages blade |68 and closes contacts |69, .|"|0. The waste gate I9 isopened and the turbine speed and the back pressure decrease. When theexhaust back pressure falls slightly below the maximum, the pin |66moves left and contacts |69, |10 `open and contacts |30, |3| closeagain, this cycle being repeated so long as the back pressure tends toexceed the maximum. If the maximum is not exceeded, control of the wastegate I9 is returned to the regulator 30. In this way, the waste isopened no llonger than necessary to avoid excessive back pressure. Thecontrol circuits described in this paragraph are shown in simplifiedform in Fig. 2 under E. Control by Exhaust Back Pressure.

It is apparent from the foregoing that the present system of controlprovides speed responsive means for xing the minimum and maximum speedsof the turbine. As an ascent is made, the regulator sets the throttlevalve at a position which will allow the engine to receive out of thetotal available supercharger pressure (with minimum speed operation ofthe supercharger I6) that which has been pre-selected for the operationof the engine. As altitude increases the throttle valve opening in- Whenthe throttle is 95% open, the pressure regulating device takes over thecontrol of the turbine speed to increase it from minimum to maximum toenable the airplane to climb to an altitude in excess of that whichKwould be critical for minimum speed operation of the supercharger |6.At maximum rated speed of the turbine, the speed responsive means takesover the control to maintain the maximum speed. However, if, beforemaximum speed of the turbine is reached, the exhaust back pressureexceeds the maximum allowable value, then maximum exhaust back pressurecontrol will yield to control .by the pressure regulating device untilthe regulator does not maintain the throttle valve I4 wide open. Thencontrol of the regulating device yields to minimum speed control.

While the embodiment of the present invention as herein disclosed,constitutes a preferred form, it is to be understood that other formsmight be adopted, all coming within the scope of the claims whichfollow.

What is claimed is as follows:

1. A system of control for an airplane engine having a superchargerdriven by an engine exhaust turbine and a valve controlling the pressureof fuel mixture admitted to the engine and an exhaust Waste-gate valvecontrolling the speed of the turbine and supercharger comprising, incombination, a servo-motor for moving the waste-gate, speed responsivemeans normally operative for controlling the servo-motor to obtain agoverned minimum turbine speed, speed responsive means for controllingthe servo-motor to obtain a governed maximum turbine speed, a throttlevalve regulator responsive to intake pressure for effecting a movementof the throttle valve sufficient to maintain a selected pressure withchanging altitude, manually operable means for partially opening thethrottle valve and for selecting an intake pressure to be maintained bythe regulator, means brought under the control of the regulator when thethrottle valve has been moved substantially wide open for causing theservo-motor to move the waste-gate toward closed position to effectwhatever increase in turbine speed is required to maintain the selectedpressure with wide open throttle until maximum speed is reached, andmeans for limiting the operation of the servomotor to close thewaste-gate when the exhaust back pressure exceeds a certain amount.

2. A system of control for an airplane engine having a superchargerdriven by an engine exhaust turbine and a valve controlling the pressureof fuel mixture admitted to the engine and an exhaust waste-gate valvecontrolling the speed of the turbine and supercharger comprising, incombination, a servo-motor for moving the waste-gate, a regulatorresponsive to intake pressure for positioning the throttle valve inorder to maintain a selected intake pressure with changing altitude,manually operable means for selecting the pressure to be maintained bythe regulator, speed responsive means normally eI- fective to controlthe servo-motor for positioning the waste gate for minimum governedspeed of the supercharger, means rendered effective upon movement of thethrottle valve by the regulator to Wide open position for overriding theminimum speed control means and for causing the servo-motor to close thewaste gate as altitude increases in order to increase turbine speed andsupercharger pressure, speed responsive means which overrides control ofthe servomotor by the regulator when a certain maximum turbine speed isattained and which so controls the servo-motor as to position the wastegate for maximum turbine speed, and exhaust back pressure responsivemeans which overrides control of the servo-motor by the regulator when amaximum allowable exhaust back pressure is reached and causes theservo-motor to limit the closing of the waste gate.

3. A system of control for an airplane engine havingv a superchargerdriven by an engine exhaust turbine and a valve controlling the pressureof fuel mixture admitted to the engine and an exhaust Waste-gate valvecontrolling the speed of the turbine and supercharger comprising, incombination, a servo-motor for moving the waste-gate, speed responsivemeans normally operative for controlling the servo-motor to obtain agoverned minimum turbine speed, speed responsive means for controllingthe servo-motor to obtain a governed maximum turbine speed, a throttlevalve regulator responsive to intake pressure for eiecting a movement ofthe throttle valve suiicient to maintain a selected pressure withchanging altitude, manually operable means for partially opening thethrottle valve and for selecting an intake pressure to be maintained bythe regulator, and means brought under the controlr of the regulatorwhen the throttle valve hasbeen moved substantially wide open forcausing the servo-motor to move the waste-gate toward closedposition toeffect whatever increase in turbine speed is required to maintain theselected pressure with wide open throttle until maximum speed isreached.

4. A system of control for an airplane engine having a superchargerdriven by an engine exhaust turbine and a valve controlling the pressureof fuel mixture admitted to the engine and an exhaust Waste-gate valvecontrolling the speed of the turbine and supercharger comprising, incombination, a servo-motor for moving the Waste-gate, a regulatorresponsive to intake pressure for positioning the throttle valve inorder to maintain a selected intake pressure with changing altitude,manually operable means for selecting the pressure to be maintained bythe regulator, speed responsive means normally effective to control theservo-motor for positioning the waste-gate for minimum governed speedofV the supercharger, means rendered eective upon movement of thethrottle valve by the regulator to wide open position for overriding theminimum speed control means and for causing the servo-motor to close thewaste-'gate as altitude increases in order to increase turbine speed andsupercharger pressure, and speed responsive means which overridescontrol of the servo-motor by the regulator when a certain maximumturbine speed is attained and which so controls the servo-motor as toposition the Waste-gate for maximum turbine speed.

5. A system of control for an airplane engine having a superchargerdriven by an engine exhaust turbine and a valve controlling the pressureof fuel mixture admitted to the engine and an exhaust waste-gate valvecontrolling the speed of the turbine and supercharger comprising, incombination, aservo-motor for moving the wastegate, speed responsivemeans normally operative for controlling the servo-motor toV obtain agoverned minimum turbine speed, speed responsive means for controllingthe servo-motorto obtain a governed maximum turbine speed, a throttlevalve regulator responsive to intake pressure for eiecting a movement ofthe throttle valve suiiicient to maintain a selected pressure withchanging altitude, manually operable means for partially opening thethrottle valve and for selecting an intake pressure to be maintained bythe regulator, means brought under the control of the regulator when thethrottle valve has been moved to a certain open position for causing theservomotor to move the waste-gate toward closed position to eiectWhatever increase in turbine speed isrequired to maintainv the selectedpressure 10 with that throttle opening until maximum speed is reached,and means under the control of the regulator for obtaining a rapidacceleration of the turbine in response to movement by the regulator ofthe throttle valve to'a certain position of greater opening inconsequence of the abrupt' change in pressure selection to a relativelyhigh pressure. i i Y 6. A system of control for an airplane enginelhaving a superoharger driven by an engine exhaust' turbine and a valvecontrolling the pressure of fuel mixture admitted to the engine and anexhaust waste-gate valve controlling the speed of the turbine andsup'ercharger comprising, in combination; a servo-motor for moving thewastegate, a regulator responsive to intake pressure for positioning thethrottle valve in order tomaintain a selected .intake pressure withchanging altitude, manually operable means for selecting the pressure tobe maintained by the regulator, speed responsive means normallyeffectivev to control the servo-motor for positioning the wastegate forminimum governed speed of the supercharger, means rendered effectiveupon movement of the throttle valve by the regulator to a certain openposition for overriding the minimumV speed control means and for causingthe servoinoto'r to close the waste-gate as altitude increases in orderto increase turbine speed and supercharger pressure, andspe'ed.responsive means which overrides control of the servo-motor ,bythe regulator when a certain maximum" speed is attained and which socontrols the servo-motor as to position the waste gate for maximumturbine speed. Y

'7. A system' of `control for an airplane engine having a superchargerdriven by an engine exhaust turbine and a valve controllingl thepressure of fuel mixture admitted to the engine and an exhaustVwaste-gate valve controlling the speed of' theI turbine andsupercharger comprising, in' combination, a servo-motor for moving theWasteg'ate, speedr responsive means normally operative for controllingthe servo-motor to obtain a governedA minimum turbine speed, speedresponsive means'for controlling the servo-motor to obtain agovernedmaximum turbine speed, a throttley valvev regulator responsiveto intake pressure for eiectin'g a movement of the throttle Vvalvesulicient to maintain a selected pressure with changing altitude,manually operable means for partia'llyV opening the throttle valve andfor select"- ing an intake pressure to be maintained by 'the regulator,means brought under the control of the regulator when' the throttlevalve `has been moved to a certain' 'open position for causing theservo-motor to move the Waste-gate toward closed positionl to elec'twhatever increase in turbine' speed is required to maintain the selectedpres-V sure With that throttle opening until maximum speed is reached,means under the control of the regulator for obtaining a rapidacceleration of the turbine in response to movement bythe regulator ofthe throttle' valve to a certain position' of greater opening inconsequence of the abrupt change in pressure selection to a relativelyhigh pressure, and means for limiting the operation of the servo-motorto close the Waste-gate when the exhaust back pressure exceeds a certainamount.

8. A system of control for an airplane engine having a superchargerdriven by an engine exhaust turbine and a valve controlling the pressureof fuel mixture admitted to the engine and' an exhaust Waste-gate valvecontrolling the speed of the turbine and supercharger comprising, incombination, a servo-motor for moving the wastegate, a regulatorresponsive to intake pressure for positioning the throttle valve inorder to maintain a selected intake pressure with changing altitude,manually operable means for selecting the pressure to be maintained bythe regulator, speed responsive means normally effective to control theservo-motor for positioning the wastegate for minimum governed speed ofthe supercharger, means rendered effective upon movement of the throttlevalve by the regulator to a certain open position for overriding theminimum speed control means and for causing the servomotor to close theWaste-gate as altitude increases in order to increase turbine speed andsupercharger pressure, means under the control of the regulator forobtaining a rapid acceleration of the turbine in response to movement bythe regulator of the throttle valve to a certain position of greateropening in consequence of the abrupt change in pressure selection to arelatively high pressure, speed responsive means which overrides controlof the servo-motor by the regulator when a certain maximum speed isattained and which so controls the servo-motor as to position the wastegate for maximum turbine speed, and exhaust back pressure responsivemeans which overrides control of the servo-motor by the regulator when amaximum allowable exhaust back pressure is reached and causes theservo-motor to limit the closing of the waste-gate.

9. A system of control for a supercharged internal combustion enginecomprising an intake duct having a throttle valve for controlling theflow of air or fuel-mixture to the engine, a throttle valve regulatorwhich is manually conditioned for the selection of an intake pressure tobe maintained and which is responsive to engine intake pressure so thatthe valve is positioned to correct for divergencies from the selectedpressure, an exhaust turbine-driven-supercharger connected with theengine intake, a turbine-waste gate for controlling the speed of thesupercharger, a reversible electric motor for moving the waste gate andhaving a first circuit for effecting closing of the waste gate toincrease supercharger speed and a second circuit for effecting openingof the waste gate to decreasesupercharger speed, a first-circuit controlswitch which is normally closed and which opens at a certain minimumsupercharger speed, a second-circuit control switch which is normallyopen and which closes when the minimum speed is exceeded, a firstcircuitcontrol switch which is normally open and which closes at a certain openposition of the throttle valve, a second-circuit control switch which isnormally closed and which opens at a lesser open position of thethrottle valve, a first circuit control switch which is normally closedand which opens when the supercharger speed exceeds a certain maximumand a second-circuit control switch which is normally open and whichcloses when the maximum speed is reached.

l0. A system of control for a supercharged internal combustion enginecomprising an intake duct having a throttle valve for controlling theiiow of air or fuel-mixture to the engine, a throtthe valve regulatorwhich is manually conditioned for the selection of an intake pressure tobe maintained and which is responsive to engine intake pressure so thatthe valve is positioned to correct for divergencies from the selectedpressure, an exhaust turbine-driven-supercharger connected with theengine intake, a turbine waste gate for controlling the speed of thesupercharger, a reversible electric motor for moving the waste gate andhaving a rst circuit for effecting closingof the waste gate to increasesupercharger speed and a second circuit for effecting opening of thewaste gate to decrease supercharger speed, a rstcircuit control switchwhich is normally closed and which opens at a certain minimumsupercharger speed, a second-circuit control switch which is normallyopen and which closes when the minimum speed is exceeded, afirst-circuit control switch which is normally open and which closes ata certain open position of the throttle valve, a second-circuit controlswitch which is normally closed and which opens at a lesser openposition of the throttle valve, a first circuit control switch which isnormally closed and which opens when the supercharger speed exceeds acertain maximum, a second-circuit control switch which is normally openand which closes when the maximum speed is reached, a rst-circuitcontrol switch normally closed and opening in response to attainment ofa certain exhaust pressure, and a second-circuit control switch normallyopen and closed in response to exceeding said certain exhaust pressure.

11. A system of control for a supercharged internal combustion enginecomprising an intake duct having a throttle valve for controlling theflow of air or fuel-mixture to the engine, a throttle valve regulatorwhich is manually conditioned for the selection of an intake pressure tobe maintained and which is responsive to engine intake pressure so thatthe valve is positioned to correct for divergencies from the selectedpressure, an exhaust turbine-driven-supercharger connected with theengine intake, a turbine-waste gate for controlling the speed of thesupercharger, a reversible electric motor for moving the waste gate andhaving a rst circuit for effecting closing of the waste gate to increasesupercharger speed and a second circuit for effecting opening of thewaste gate to decrease supercharger speed, a first-circuit controlswitch which is normally closed and which opens at a certain minimumsupercharger speed, a second-circuit control switch which is normallyopen and which closes when the minimum speed is exceeded, a firstcircuitcontrol switch which is normally open and which closes at a certain openposition of the throttle valve, a second-circuit control switch which isnormally closed and which opens at a lesser open position of thethrottle valve, a first circuit control switch which is normally closedand which opens when the supercharger speed exceeds a certain maximiun,a second-circuit control switch which is normally open and which closeswhen the maximum speed is reached, an electrically operated device forclosing the wastegate, and a normally open switch closed in response toa wide opening of the throttle valve for rendering the device operative.

l2. A system of control for a supercharged internal combustion enginecomprising an intake duct having a throttle valve for controlling theflow of air or fuel-mixture to the engine, a throttle valve regulatorwhich is manually conditioned for the selection of an intake pressure tobe maintained and which is responsive to engine intake pressure so thatthe valve is positioned to correct for divergencies from the se-A lectedpressure, an exhaust turbine-driven-supercharger connected with theengine intake, a turbine-waste gate for controlling the speed of thesupercharger, a reversible electric motor for mov-4 13 1 ing the wastegate and having a rst circuit for effecting closing of the waste gate toincrease supercharger speed and a second circuit for effecting openingof the waste gate to decrease supercharger speed, a first relay forcontrolling the first circuit of the motor, a second relay forcontrolling the second circuit of the motor, a current source; a seriescircuit comprising the source, the iirst relay and a normally closedSwitch opening in response to attainment of minimum supercharger speed;a series circuit comprising the source, the second relay, a normallyclosed switch opening in response to opening of the throttle valve to acertain extent, a normally closed switch opening in response toattainment of a certain maximum supercharger speed, and a normally openswitch closed 'in response to exceeding a certain minimumjfsuperchargerspeed; a circuit paralleling the normally closed throttle responsiveswitch and the normally closed maximum speed responsive'dswitch andincluding a normally open switch closed in response to the attainment ofsaid maximum supercharger speed and a circuit paralleling the secondrelay and normally closed throttle responsive switch and including therst relay and a normally open switch which is closed in response toopening of the throttle to an extent greater kthan iirst mentioned.

13. A system of control for a supercharged internal combustion enginecomprising an intake duct having a throttle valve for controlling the owof air or fuel-mixture to the engine, a throttle valve regulator whichis manually conditioned for the selection of an intake pressure to bemaintained and which is responsive to engine intake pressure so that thevalve is positioned to correct for divergencies from the selectedpressure, an exhaust turbine-driven-supercharger connected with theengine intake, a turbinewaste gate for controlling the speed ofthe`super charger, a reversible electric motor for moving the waste gateand having a first circuit for eiecting closing of the waste gate toincrease supercharger speed and a second circuit for effecting openingof the waste gate to decrease supercharger speed, a first relay forcontrolling the first circuit of the motor, a second relay forcontrolling the second circuit of the motor, a current source; a seriescircuit comprising the source, the first relay and a normally closedswitch opening in response to attainment of minimum supercharger speed;a series circuit comprising the source, the second relay, a normallyclosed switch opening in response to the opening of the throttle valveto a certain extent, a normally closed switch opening in response to theattainment of a certain exhaust pressure, a normally closed switchopening in response to the attainment of a certain maximum superchargerspeed and a normally open switch closed1 in response to exceeding acertain minimum supercharger speed; a circuit paralleling the normallyclosed throttle responsive switch and the normally closed exhaustpressure responsive switch and the normally closed maximum speedresponsive switch and including a normally open switch closed inresponse to the attainment of said maximum supercharger speed; a circuitparalleling the normally closed throttle responsive switch and saidnormally closed exhaust-pressure responsive switch and including anormally open switch closed in response to exceeding said predeterminedexhaust pressure; a circuit paralleling the second relay and normallyclosed throttle responsive switch and including the iirst relay and anormally open switch which is closed in response to opening of thethrottle to an extent greater than iirst mentioned and a circuitcontrolled by the last mentioned throttle controlled switch andparalleling the iirst relay and including an elec- ,trically operateddevice for closing the wastegate independently of the motor and anormally open switch closed in response to full opening of the throttlevalve.

14. A system of control for a supercharged internal combustion enginecomprising an intake duct having a throttle valve for controlling thenow of air or fuel-mixture to the engine, a throttle valve regulatorwhich' is inanually conditioned for the selection of an intake pressureto be maintained and which is"`responsive to engine intake pressure sothat"'tlie valve is positioned to correct for divergencies from theselected pressure, an exhaust turbine-driven-supercharger connected withthe engine intake, a turbinewaste gate for controlling the speed of thesupercharger, a reversible electric motor for moving the waste gate andhaving a nrst circuit for effecting closing of the waste gate toincrease supercharger speed and a second circuit for effecting openingof the waste gate to decrease supercharger speed, a rst relay forcontrolling the first circuit of the motor, a second relay forcontrolling the second circuit of the motor, a current source; a seriescircuit comprising the source, the first relay and a normally closedswitch opening in response to attainment of minimum supercharger speed;a series circuit comprising the source, the second relay, a normallyclosed switch opening in response to the opening of the throttle valveto a certain extent, a normally closed switch opening in response to theattainment of a certain exhaust pressure, a`

normally closed switch opening in response to the attainment of acertain maximum supercharger speed and a normally open switch closed inresponse to exceeding a certain minimum supercharger speed; a circuitparalleling the normally closed throttle responsive switch and thenormally closed exhaust pressure responsive switch and the normallyclosed maximum speed responsive switch and including a normally openswitch closed in response to the attainment of said maximum superchargerspeed; a circuit paralleling the normally closed throttle responsiveswitch and said normally closed exhaustpressure responsive switch andincluding a normally open switch closed in response to exceeding saidpredetermined exhaust pressure; and a circuit paralleling the secondrelay and normally closed throttle responsive switch and including therst relay and a normally open switch which is closed in response toopening of the throttle to an extent greater than first mentioned.

PAUL L. SCHNEIDER.

REFERENCES CITED UNITED STATES PATENTS Name Date Pateras Pescara Aug. 4,1942 Number

